The main objective of this trial was to evaluate the combination of subcutaneous (SC) interleukin-2 (IL-2) with interferon α-2a (IFN-α) in the treatment of patients with metastatic renal cell carcinoma (MRCC) compared with a previous trial that used continuous-infusion IL-2 and IFN-α with identical schedules and dosages.
Between April, 1997 and January, 1998, 66 patients with MRCC received SC IL-2 at a dose of 9 × 106 IU/m2 twice daily for 5 days during 2 induction cycles and during 4 additional cycles, with a 3-week rest between cycles. Each induction cycle consisted of two 5-day courses of IL-2 separated by a 9-day break. IFN-α at a dose of 6 × 106 IU per day three times per week was given during induction cycles and additional cycles.
All patients were assessable for response and toxicity. The median follow-up was 43 months. Thirty-five patients (51%) and 43 patients (63%) received ≥ 80% of the planned induction doses of IL-2 and IFN-α, respectively. Five patients achieved objective responses (7.6%; 95% confidence interval [95%CI], 2.5–16.8%), with two complete responses. The median survival was 14 months (95%CI, 11.3–16.7 months). Fifty-three patients (80%) had at least one episode of Grade 3 toxicity related to treatment. Twenty-two patients developed Grade 4 toxicities, which included hypotension (24% of patients), decreased performance status (6% of patients), dyspnea (3% of patients), and mucositis (3% patients) as well as fever, ventricular tachycardia, and anemia.
The current results seem to indicate reduced efficacy and higher toxicity rates with SC IL-2 plus IFN-α compared with the results from a previous trial that used an identical regimen with IV IL-2 administration. Although SC IL-2 regimens are used widely, their interest remains to be determined. Cancer 2002;95:2324–30. © 2002 American Cancer Society.